2009 Acura TSX Engine Oil Capacity: What Every Owner Needs to Know for a Healthy Engine

If you own a 2009 Acura TSX, one of the most critical maintenance tasks you’ll perform is keeping its engine properly lubricated—and that starts with understanding its engine oil capacity. After years of working with Honda and Acura vehicles, including countless 2009 TSX models, I can confirm: the 2009 Acura TSX requires 4.2 quarts (approximately 4 liters) of engine oil to operate at peak performance. This capacity accounts for both the engine’s internal components and a new oil filter during a full oil change. While minor variations might exist based on minor manufacturing differences or after extended use, 4.2 quarts is the standard specification outlined by Acura’s engineering team for this model year.

Why does this number matter so much? Let’s break it down.

Why Engine Oil Capacity Is Non-Negotiable for Your 2009 TSX

The 2009 TSX is powered by a 2.4-liter K24 inline-4 cylinder engine, renowned for its balance of power and efficiency. Like all internal combustion engines, the K24 relies on oil to perform four vital functions: lubricating moving parts (reducing friction), cooling hot components (transferring heat away from critical areas), cleaning sludge and debris (via the oil filter), and sealing gaps between pistons and cylinders (maintaining compression).

If you add too little oil—say, 3.5 quarts instead of 4.2—the engine’s components will rub against each other without adequate lubrication. Over time, this friction causes metal fatigue, overheating, and potentially catastrophic damage like scored cylinder walls or seized bearings. On the flip side, overfilling (adding 4.5 quarts or more) creates excessive pressure in the crankcase. This pressure can force oil past seals and gaskets, leading to leaks, blown gaskets, or damage to the catalytic converter (as oil vapor can clog its delicate honeycomb structure).

In short: the 4.2-quart capacity isn’t arbitrary—it’s engineered to keep your TSX’s engine running smoothly for years.

How to Confirm Your 2009 TSX’s Exact Oil Capacity

While 4.2 quarts is the standard, there are rare scenarios where your vehicle might need slightly more or less. For example, if your TSX has an aftermarket oil cooler or modified components, the capacity could change. To be 100% sure, follow these steps:

  1. Check Your Owner’s Manual: The definitive source for your vehicle’s specifications, the 2009 TSX owner’s manual includes a “Maintenance” section with exact oil capacity details. Look for phrases like “oil change capacity” or “engine oil quantity.” In most copies, you’ll find it listed as “4.2 US quarts (4.0 L) with filter.”

  2. Contact an Acura Dealer: If your manual is lost or unclear, reach out to an authorized Acura dealership. Their service departments have access to factory technical bulletins and can confirm the capacity for your specific VIN (vehicle identification number).

  3. Perform a Practical Check: If you’re changing your oil yourself, you can verify the capacity by draining the old oil into a clean container, measuring it, and noting how much you add back to reach the “Full” mark on the dipstick. This hands-on method accounts for any residual oil left in the engine (typically a few ounces) and ensures you hit the mark accurately.

Step-by-Step: Checking and Adding Oil to Your 2009 TSX

Even if you know the 4.2-quart capacity, improper technique when adding oil can lead to mistakes. Here’s how to do it safely and correctly:

Step 1: Prepare the Vehicle

  • Park your TSX on a flat, level surface and let the engine cool for at least 30 minutes. Hot oil expands and can spray when you remove the drain plug or dipstick, causing burns.
  • Gather supplies: a new oil filter (Acura part number 904-0648 or equivalent), a drain pan, a funnel, a wrench (for the drain plug), rags, and 4.2 quarts of the recommended oil (we’ll cover types next).

Step 2: Drain the Old Oil

  • Locate the oil drain plug underneath the engine (it’s on the bottom of the oil pan, usually near the front of the car). Place the drain pan directly beneath it.
  • Use the wrench to loosen the drain plug counterclockwise. Once loose, unscrew it by hand and quickly move it aside to avoid dripping oil on your hands or the ground.
  • Allow the old oil to drain completely (this takes 5–10 minutes). While waiting, remove the old oil filter (located on the side of the engine block; use a filter wrench if it’s tight) and replace it with the new one. Hand-tighten the new filter (do not over-tighten—this can crack the seal).

Step 3: Reinstall the Drain Plug

  • Clean the drain plug and its gasket (if it has one) with a rag to remove dirt and old oil. Screw the drain plug back into place by hand, then tighten it with the wrench until it’s snug. Do not overtighten—over-torquing can strip the oil pan threads (a common and costly mistake).

Step 4: Add New Oil

  • Locate the oil filler cap on top of the engine (it’s labeled “Oil” and typically near the intake manifold). Place the funnel into the filler hole.
  • Slowly pour 3 quarts of oil into the engine. Wait 1–2 minutes for the oil to settle, then check the dipstick. Pull it out, wipe it clean, reinsert it fully, and pull it out again. The oil level should be between the “L” (Low) and “F” (Full) marks.

Step 5: Top Off and Verify

  • If the level is below “L,” add small amounts (1/4 quart at a time) and recheck the dipstick. Stop when the oil reaches just below “F”—overfilling here can cause issues under high RPMs.
  • Once the level is correct, reinstall the oil filler cap tightly. Start the engine and let it idle for 1–2 minutes. Watch the oil pressure gauge (on the dashboard); it should rise to a normal range within 10–15 seconds. If it doesn’t, turn off the engine immediately—this could indicate a problem with the oil pump or a blocked filter.

The Right Oil Type for Your 2009 TSX: Don’t Cut Corners

Using the correct oil isn’t just about capacity—it’s about protecting your engine. The 2009 TSX’s K24 engine is designed to run on 5W-20 viscosity oil that meets or exceeds two key certifications:

  • API SN (or higher): The American Petroleum Institute’s SN rating ensures the oil provides superior protection against wear, sludge, and deposits. Newer TSX models may require SP or SN Plus, but the 2009 TSX is optimized for SN.
  • ILSAC GF-5: The International Lubricant Standardization and Approval Committee’s GF-5 standard focuses on fuel efficiency and high-temperature performance, which aligns with the K24’s efficient design.

Always choose full-synthetic oil for your TSX. Synthetic oils flow better in cold weather (critical for cold starts, which are hard on engines) and maintain their protective properties longer than conventional oils. For the 2009 TSX, synthetic oil can extend your oil change interval to 7,500 miles or 12 months (under normal driving conditions)—though we’ll cover when to adjust that later.

When to Change Your Oil: Follow the 7,500-Mile Rule (But Be Flexible)

Acura recommends changing the oil in your 2009 TSX every 7,500 miles or 12 months, whichever comes first. This interval is based on “normal” driving conditions: mostly highway miles, moderate temperatures, and no extreme loads (like towing or frequent short trips).

However, if you drive under “severe” conditions—common for many TSX owners—shorten the interval to 5,000 miles or 6 months. Severe conditions include:

  • Frequent short trips (less than 10 miles, especially in cold weather, where oil doesn’t fully warm up).
  • Driving in extreme heat (over 90°F) or cold (below -20°F).
  • Towing a trailer, hauling heavy loads, or driving on rough/dusty roads.
  • Idling for long periods (e.g., stop-and-go traffic in a city).

To track your oil changes, keep a log in your glove box or use a maintenance app. Note the date, mileage, oil type, and filter used—this helps you stay consistent and catch issues early (like oil consumption, which could signal a leak or worn piston rings).

Common Myths About Oil Capacity (and Why They’re Wrong)

Let’s debunk a few misconceptions we’ve heard from TSX owners over the years:

  • Myth 1: “I can just top off my oil whenever it looks low.”
    False. The dipstick only shows the current level—not the total capacity. If you consistently add small amounts without draining the old oil, contaminants (like metal shavings or sludge) will accumulate, reducing the oil’s effectiveness. Always do a full oil change (drain and refill) to maintain capacity and cleanliness.

  • Myth 2: “Using a higher viscosity oil (like 10W-30) won’t hurt.”
    False. The K24 engine is engineered for 5W-20. Thicker oil (10W-30) doesn’t flow as well in cold weather, increasing wear on startup. It can also create excessive pressure in the crankcase, leading to leaks or seal damage. Stick to the manufacturer’s recommendation.

  • Myth 3: “Old oil is fine if I just add new oil to it.”
    False. Old oil loses its lubricating properties and breaks down over time, even if you top it off. Mixing old and new oil dilutes the additive package (which fights sludge and wear), reducing its ability to protect your engine. Always drain the old oil completely before adding new.

Final Thoughts: Your TSX’s Engine Deserves the Right Care

Understanding the 2009 Acura TSX’s 4.2-quart engine oil capacity is just one piece of the maintenance puzzle—but it’s a critical one. By using the right oil type, checking levels regularly, and following Acura’s guidelines, you’ll ensure your TSX’s K24 engine runs smoothly, efficiently, and reliably for years to come.

Remember: your car’s engine is its heart. Treat it with care, and it will reward you with thousands of miles of driving pleasure. If you’re ever unsure about an oil change, consult a trusted mechanic or Acura dealer—they’re there to help you keep your TSX in top condition.

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